Other Proposed Uses

Methionine is an essential amino acid—one of the building blocks of proteins and peptides that your body cannot manufacture from other chemicals. The body uses methionine to manufacture
creatine
and uses the sulfur in methionine for normal metabolism and growth.

One preliminary study suggests that methionine can prevent bacteria from sticking to urinary tract cells,
1
which may make it useful for preventing bladder infections. (
Cranberry
juice is thought to help reduce the incidence of bladder infections in a similar fashion.)

Requirements/Sources

Depending on your body weight, you need between 800 and 1,000 mg of methionine daily for normal health. Deficiency is unlikely because enough methionine is generally available from the diet.

Meat, fish, dairy products, and other high-protein foods are good sources of methionine.

Therapeutic Dosages

A proper therapeutic dosage of methionine has not been determined. One study relating to urinary tract infections used a dosage of 500 mg 3 times daily. A study enrolling people with HIV used a dose of 800 mg three times daily.

Therapeutic Uses

Because it seems to discourage bacteria from sticking to the wall of the bladder, methionine has been suggested as a treatment for recurrent
bladder infections
.
2
However, the evidence that it works is limited to one small trial without a placebo control. (For information on why placebo-controlled trials are essential to prove a treatment effective, see
Why Does This Database Depend on Double-Blind Studies?
)

One double-blind study found equiviocal evidence that methionine supplements taken at a dose of 2.4 g per day might improve immune function in people with
HIV
.
8

One study on rats suggests that methionine might protect the liver against the damaging effects of acetaminophen poisoning.
3
On this slim basis, methionine has been proposed as a
general liver protectant
. However, in this particular study, the action of methionine was more to fight acetaminophen specifically than to protect the liver in general.

Very preliminary evidence suggests methionine might be helpful in treating
Parkinson's disease
.
4,5
However, this should not be attempted except under physician supervision; see Safety Issues.

Safety Issues

Methionine is thought to be generally safe. However, the maximum safe dosages for young children, pregnant or nursing women, or those with serious liver or kidney disease have not been established.

Like other amino acids, methionine may interfere with the absorption or action of the drug levodopa, which is used for
Parkinson's disease
.
6

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.